In Old World primates, TRIM5-αconfers a potent block to human immunodeficiency virus type 1 (HIV-1) infection that acts after virus entry into cells (1-5). (References are listed in numerical order at the end of the specification, and are all incorporated by reference in their entireties for all purposes.) Cyclophilin A (CypA) binding to viral capsid protects HIV-1 from a similar activity in human cells (4, 6-8). Among New World primates, only owl monkeys exhibit post-entry restriction of HIV-1 (1). Paradoxically, the barrier to HIV-1 in owl monkey cells is released by capsid mutants or drugs that disrupt capsid interaction with CypA (4). HIV-1 infection is a serious problem throughout the world and there is a great need for a composition that will prevent infection of a subject by HIV-1 and for a composition that treats or ameliorates the effects of HIV-1 infection in humans.